Synthesis of Nickel Phosphide Electrocatalysts from Hybrid Metal Phosphonates.

Transition-metal phosphides (TMPs) have recently emerged as efficient and inexpensive electrocatalysts for electrochemical water splitting. The synthesis of nanostructured phosphides often involves highly reactive and hazardous phosphorous-containing compounds. Herein, we report the synthesis of nickel phosphides through thermal treatment under H2(5%)/Ar of layered nickel phenylphosphonate (NiPh) or methylphosphonate (NiMe) that act as single-source precursors. Ni12P5, Ni12P5-Ni2P, and Ni2P nanoparticles (NPs) with sizes of ca. 15-45 nm coated with a thin shell of carbonaceous material were produced. Thermogravimetric analysis coupled with mass spectrometry (TG-MS) showed that H2, H2O, P2, and -C6H5 are the main compounds formed during the transformation of the precursor under argon and no hazard phosphorous-containing compounds are created, making this a simple and relatively safe route for fabricating nanostructured TMPs. The H2 most likely reacts with the -PO3 groups of the precursor to form H2O and P2, and the latter subsequently reacts with the metal to produce the phosphide. The Ni12P5-Ni2P and Ni2P NPs efficiently catalyze the hydrogen evolution reaction (HER), with Ni2P showing the best performance and generating a current density of 10 mA cm-2 at an overpotential of 87 mV and exhibiting long-term stability. Co2P and CoP NPs were also synthesized following this method. This approach may be utilized to explore the rich metal phosphonate chemistry for fabricating phosphide-based materials for electrochemical energy conversion and storage applications.

CO oxidation at nickel centres by N2O or O2 to yield a novel hexanuclear carbonate.

Reaction of a nickel(0) carbonyl complex, K(2)[L(tBu)NiCO](2), with N(2)O generates a cyclic carbonate compound composed of six [Ni(II)(CO(3))K](+) units. The same product can also be obtained using O(2) as the oxidant in a solid-state/gas reaction. These conversions represent unique examples of a nickel-bound CO oxidation by N(2)O and O(2), respectively.

"Hexagonal molybdenum trioxide"--known for 100 years and still a fount of new discoveries.

In 1906, the preparation of "molybdic acid hydrate" was published by Arthur Rosenheim. Over the past 40 years, a multitude of isostructural compounds, which exist within a wide phase range of the system MoO3−NH3−H2O, have been published. The reported molecular formulas of "hexagonal molybdenum oxide" varied from MoO3 to MoO3·0.33NH3 to MoO3·nH2O (0.09 ≤ n ≤ 0.69) to MoO3·mNH3·nH2O (0.09 ≤ m ≤ 0.20; 0.18 ≤ n ≤ 0.60). Samples, prepared by the acidification route were investigated using thermal analysis coupled online to a mass spectrometer for evolved gas analysis, X-ray powder diffraction, Fourier transform infrared, Raman, magic-angle-spinning 1H- and 15N NMR spectroscopy, and incoherent inelastic neutron scattering. A comprehensive characterization of these samples will lead to a better understanding of their structure and physical properties as well as uncover the underlying relationship between the various compositions. The synthesized polymeric parent samples can be represented by the structural formula (NH4)(x∞)(3)[Mo(y square 1−y)O(3y)(OH)(x)(H2O)(m−n)]·nH2O with 0.10 ≤ x ≤ 0.14, 0.84 ≤ y ≤ 0.88, and m + n ≥ 3 − x − 3y. The X-ray study of a selected monocrystal confirmed the presence of the well-known 3D framework of edge- and corner-sharing MoO6 octahedra. The colorless monocrystal crystallizes in the hexagonal system with space group P6(3)/m, Z = 6, and unit cell parameters of a = 10.527(1) Å, c = 3.7245(7) Å, V = 357.44(8) Å3, and ρ = 3.73 g·cm(−3). The structure of the prepared monocrystal can best be described by the structural formula (NH4)(0.13∞)(3)[Mo(0.86 square 0.14)O2.58(OH)0.13(H2O)(0.29−n)]·nH2O, which is consistent with the existence of one vacancy (square) for six molybdenum sites. The sample MoO3·0.326NH3·0.343H2O, prepared by the ammoniation of a partially dehydrated MoO3·0.170NH3·0.153H2O with dry gaseous ammonia, accommodates NH3 in the hexagonal tunnels, in addition to [NH4]+ cations and H2O. The "chimie douce" reaction of MoO3·0.155NH3·0.440H2O with a 1:1 mixture of NO/NO2 at 100 °C resulted in the synthesis of MoO3·0.539H2O. This material is of great interest as a host of various molecules and cations.

Degradation of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking.

The stability of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking was investigated by model experiments using a spiked wholemeal wheat flour matrix. For alternariol and alternariol monomethyl ether, but not for altenuene, degradation products, formed through a sequence of hydrolysis and decarboxylation, could be identified in pilot studies. The simultaneous quantification of alternariol, alternariol monomethyl ether, altenuene, and the degradation products was achieved by a newly developed high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) multimethod. The obtained quantitative data indicate that the Alternaria mycotoxins are barely degraded during wet baking, while significant degradation occurs upon dry baking, with the stability decreasing in the order alternariol monomethyl ether>alternariol>altenuene. The novel degradation products could be detected after the wet baking of flour spiked with alternariol and in a sample survey of 24 commercial cereal based baking products.

Investigation of the fluorolysis of magnesium methoxide.

The structures of magnesium methoxide and magnesium methoxide fluoride obtained via the reaction of Mg(OCH(3))(2) with HF were investigated by single-crystal structure analysis and multinuclear solid-state NMR ((13)C and (19)F). The fluorolysis of magnesium methoxide transforms the cubane structure units in hexanuclear dicubane units containing micro(4)-fluorine atoms. The resulting Mg(6)F(2)(OCH(3))(10)(CH(3)OH)(14) compound crystallizes in two different crystalline modifications. Moreover by slow thermal decomposition of the compound Mg(6)F(2)(OCH(3))(10)(CH(3)OH)(14), it loses two outer CH(3)OH molecules and leaves crystal structure Mg(6)F(2)(OCH(3))(10)(CH(3)OH)(12). The thermal behavior of Mg(OCH(3))(2)(CH(3)OH)(3.55) and Mg(6)F(2)(OCH(3))(10)(CH(3)OH)(14) was investigated by DTA and XRD. Both compounds lose the solvated methanol completely by heating above 150 degrees C and form MgO above 600 degrees C as well as amorphous MgF(2) in the case of magnesium methoxide fluoride.

New directions in the preparation and redox chemistry of fluoride-templated tetranuclear vanadium phosphonate cage compounds, M(n+)[(V2O3)2(RPO3)4

A new and simple preparation method for fluoride-templated tetranuclear vanadium phosphonate cage compounds, M(n+)[(V2O3)2(RPO3)4

Structural insights into aluminum chlorofluoride (ACF).

The structure of the very strong solid Lewis acid aluminum chlorofluoride (ACF, AlCl(x)F(3-x), x = 0.05-0.3) was studied by IR, ESR, Cl K XANES, (19)F MAS NMR, and (27)Al SATRAS NMR spectroscopic methods and compared with amorphous aluminum fluoride conventionally prepared by dehydration of alpha-AlF(3) x 3H(2)O. The thermal behavior of both compounds was investigated by DTA and XRD. In comparison to ACF, amorphous AlF(3) prepared in a conventional way is not catalytically active for the isomerization reaction of 1,2-dibromohexafluoropropane, which requires a very strong Lewis acid. Both compounds are mainly built up of corner-sharing AlF(6) octahedra forming a random network. The degree of disorder in ACF is higher than in amorphous AlF(3). Terminal fluorine atoms were detected in ACF by (19)F NMR. The chlorine in ACF does not exist as a separate, crystalline AlCl(3) phase. Additionally, chlorine-containing radicals, remaining from the synthesis, are trapped in cavities of ACF. These radicals are stable at room temperature but do not take part in the catalytic reaction.